{"api_version":"1","generated_at":"2026-09-26T13:26:28+00:00","cve":"CVE-2026-98101","urls":{"html":"https://cve.report/CVE-2026-98101","api":"https://cve.report/api/cve/CVE-2026-98101.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98101","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98101"},"summary":{"title":"ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()\n\npmc->sflist is read locklessly under rcu_read_lock() by\ninet6_mc_check() during packet reception in the UDP and RAW\nmulticast receive paths.\n\nip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place\nwhen adding or removing a source filter. Additionally, when expanding\nthe filter buffer, newpsl was published via rcu_assign_pointer()\nbefore writing the new source into the array.\n\nBecause 16-byte struct in6_addr writes are not atomic and array\nshifting is not synchronized with RCU readers, concurrent readers in\ninet6_mc_check() could read torn IPv6 addresses or observe\nduplicated/missed source entries.\n\nFix this by switching ip6_mc_source() to copy-on-write RCU updates:\nallocate and fully populate newpsl before publishing it via\nrcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),\nmatching ip6_mc_msfilter().\n\nAlso remove the now unused IP6_SFBLOCK macro.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:39","updated_at":"2026-09-25 11:17:39"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/2c2091e2ee93049fc513ad1e6c99d8b6c809f467","name":"https://git.kernel.org/stable/c/2c2091e2ee93049fc513ad1e6c99d8b6c809f467","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/20db91a052332ef5552bd2f651ffb9db911cf67b","name":"https://git.kernel.org/stable/c/20db91a052332ef5552bd2f651ffb9db911cf67b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c073d1b070f171d206b19c98d71739a97f15b3f1","name":"https://git.kernel.org/stable/c/c073d1b070f171d206b19c98d71739a97f15b3f1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98101","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98101","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 882ba1f73c06831f2a21044ebd8864c485ac04f2 2c2091e2ee93049fc513ad1e6c99d8b6c809f467 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 882ba1f73c06831f2a21044ebd8864c485ac04f2 20db91a052332ef5552bd2f651ffb9db911cf67b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 882ba1f73c06831f2a21044ebd8864c485ac04f2 c073d1b070f171d206b19c98d71739a97f15b3f1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 47c75e3923c8d562fea8daf0ccf31546a7bef0ea git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.10.261 5.11 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.13","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.13 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/if_inet6.h","net/ipv6/mcast.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"2c2091e2ee93049fc513ad1e6c99d8b6c809f467","status":"affected","version":"882ba1f73c06831f2a21044ebd8864c485ac04f2","versionType":"git"},{"lessThan":"20db91a052332ef5552bd2f651ffb9db911cf67b","status":"affected","version":"882ba1f73c06831f2a21044ebd8864c485ac04f2","versionType":"git"},{"lessThan":"c073d1b070f171d206b19c98d71739a97f15b3f1","status":"affected","version":"882ba1f73c06831f2a21044ebd8864c485ac04f2","versionType":"git"},{"status":"affected","version":"47c75e3923c8d562fea8daf0ccf31546a7bef0ea","versionType":"git"},{"lessThan":"5.11","status":"affected","version":"5.10.261","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/if_inet6.h","net/ipv6/mcast.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.13"},{"lessThan":"5.13","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc2","versionStartIncluding":"5.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.261","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()\n\npmc->sflist is read locklessly under rcu_read_lock() by\ninet6_mc_check() during packet reception in the UDP and RAW\nmulticast receive paths.\n\nip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place\nwhen adding or removing a source filter. Additionally, when expanding\nthe filter buffer, newpsl was published via rcu_assign_pointer()\nbefore writing the new source into the array.\n\nBecause 16-byte struct in6_addr writes are not atomic and array\nshifting is not synchronized with RCU readers, concurrent readers in\ninet6_mc_check() could read torn IPv6 addresses or observe\nduplicated/missed source entries.\n\nFix this by switching ip6_mc_source() to copy-on-write RCU updates:\nallocate and fully populate newpsl before publishing it via\nrcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),\nmatching ip6_mc_msfilter().\n\nAlso remove the now unused IP6_SFBLOCK macro."}],"providerMetadata":{"dateUpdated":"2026-09-25T10:35:52.731Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/2c2091e2ee93049fc513ad1e6c99d8b6c809f467"},{"url":"https://git.kernel.org/stable/c/20db91a052332ef5552bd2f651ffb9db911cf67b"},{"url":"https://git.kernel.org/stable/c/c073d1b070f171d206b19c98d71739a97f15b3f1"}],"title":"ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98101","datePublished":"2026-09-25T10:35:52.731Z","dateReserved":"2026-09-25T10:25:14.315Z","dateUpdated":"2026-09-25T10:35:52.731Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:39","lastModifiedDate":"2026-09-25 11:17:39","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98101","Ordinal":"1","Title":"ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()","CVE":"CVE-2026-98101","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98101","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()\n\npmc->sflist is read locklessly under rcu_read_lock() by\ninet6_mc_check() during packet reception in the UDP and RAW\nmulticast receive paths.\n\nip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place\nwhen adding or removing a source filter. Additionally, when expanding\nthe filter buffer, newpsl was published via rcu_assign_pointer()\nbefore writing the new source into the array.\n\nBecause 16-byte struct in6_addr writes are not atomic and array\nshifting is not synchronized with RCU readers, concurrent readers in\ninet6_mc_check() could read torn IPv6 addresses or observe\nduplicated/missed source entries.\n\nFix this by switching ip6_mc_source() to copy-on-write RCU updates:\nallocate and fully populate newpsl before publishing it via\nrcu_assign_pointer(), and reclaim the old filter via kfree_rcu(),\nmatching ip6_mc_msfilter().\n\nAlso remove the now unused IP6_SFBLOCK macro.","Type":"Description","Title":"ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()"}]}}}